Structures for providing a removable closure

ABSTRACT

A membrane lid with a surface with a substantially triangular-shaped perimeter. The perimeter includes first, second and third corner portions, wherein each corner portion is bisected by an imaginary line. The membrane lid further includes a projection with a tab and adapted to initially direct a lifting force to at least one of the corner portions. The projection either extends outwardly from the perimeter such that the projection is non-symmetrically disposed with respect to the imaginary line of any adjacent corner portion, or the projection extends non-continuously from an adjacent corner portion and is substantially symmetrically disposed with respect to the imaginary line of the adjacent corner portion. Containers are also provided with a lip having a substantially triangular-shaped horizontal cross-section. The lip includes three corner portions and three sides, wherein the sides of the lip are structured differently than the corner portions of the lip to increase the relative rigidity of the sides with respect to the corner portions such that the corner portions and the sides are adapted to exhibit a substantially uniform reaction pressure when applying a membrane lid to the lip of the container.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. ProvisionalApplication Nos. 60/248,026 and 60/248,340, each filed Nov. 13, 2000,and each application entirely incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to providing closure for acontainer, and more particularly, structures for providing a removableclosure.

BACKGROUND OF THE INVENTION

[0003] Preshaped snack pieces are typically frangible and might befragile and easily broken during packaging, shipping and/or otherhandling operations. Conventional packaging techniques provide bagsand/or boxes that can permit a significant number of the snack pieces tobreak or crush prior to consumption. The well known Pringles® shapedpotato chip snack pieces, a product of The Procter & Gamble Company,Cincinnati, Ohio, are individual snack pieces having a “saddle” shapeand are packaged in a manner which overcomes disadvantages of the priorart. The Pringles® snack pieces have conventionally been packaged as asingle nested stack in a cylindrical container which provides enhancedprotection during packaging, shipping and/or other handling. As aresult, the Pringles® snack pieces are typically presented to theconsumer without breakage.

[0004] There is a continuing need for user-friendly, relativelyinexpensive containers for packaging frangible snack pieces to provideprotection during packaging, shipping and/or other handling. It isfurther desired to provide hermetically sealed containers that provideoxygen and moisture protection to prevent spoilage of the snack piecescontained therein.

[0005] It might also be desirable to provide such inexpensive containersfor other types of frangible and/or fragile articles to reduce breakageof the articles during packaging, shipping and/or other handling, tomaintain desirable properties of the articles, and to provide auser-friendly package.

SUMMARY OF THE INVENTION

[0006] Accordingly, the present invention provides various structuresfor providing a removable closure for a container.

[0007] In one embodiment, a membrane lid is provided. The membrane lidincludes a surface with a substantially triangular-shaped perimeter. Theperimeter includes first, second and third corner portions, wherein eachcorner portion is bisected by an imaginary line. The membrane lidfurther includes a projection with a tab and adapted to initially directa lifting force to at least one of the corner portions. The projectioneither extends outwardly from the perimeter such that the projection isnon-symmetrically disposed with respect to the imaginary line of anyadjacent corner portion, or the projection extends non-continuously froman adjacent corner portion and is substantially symmetrically disposedwith respect to the imaginary line of the adjacent corner portion.

[0008] In another embodiment, a container is provided with a lip havinga substantially triangular-shaped horizontal cross-section. The lipincludes three corner portions and three sides, wherein the sides of thelip are structured differently than the corner portions of the lip toincrease the relative rigidity of the sides with respect to the cornerportions such that the corner portions and the sides are adapted toexhibit a substantially uniform reaction pressure when applying amembrane lid to the lip of the container.

[0009] The membrane lids, container lips and containers according to thepresent invention are advantageous for packaging articles, such assubstantially triangular-shaped articles to prevent breakage of thearticles. In one example, the structures provided herein are useful forpackaging tortilla chips and the like to conveniently provide consumerswith a product having minimum breakage prior to consumption whileproviding an extended shelf life.

[0010] The membrane lids according to the invention allow application ofan over-cap with high reliability and minimal interference with themembrane lid. The membrane lids of the invention may be convenientlyremoved when desired yet avoid inadvertent removal during packaging,shipping or other handling. The container lips according to theinvention further allow the formation of a reliable and durable hermeticseal with the membrane lid and contribute to over-cap retention, evenwhen containers employing the lip are subjected to pressuredifferentials, for example at high altitudes.

[0011] Additional objects and advantages of the invention will be morefully apparent in view of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following detailed description will be more fully understoodin view of the drawings in which:

[0013]FIG. 1 is a top plan view of one embodiment of a membrane lidaccording to the invention;

[0014]FIG. 2A is a top plan view of a second embodiment of a membranelid according to the invention;

[0015]FIG. 2B is a partial plan view of a third embodiment of a membranelid according to the invention;

[0016]FIG. 2C is a partial plan view of a fourth embodiment of amembrane lid according to the invention;

[0017]FIG. 2D is a partial plan view of a fifth embodiment of a membranelid according to the invention;

[0018]FIG. 2E is a partial plan view of a sixth embodiment of a membranelid according to the invention;

[0019]FIG. 2F is a partial plan view of a seventh embodiment of amembrane lid according to the invention;

[0020]FIG. 2G is a partial plan view of an eighth embodiment of amembrane lid according to the invention;

[0021]FIG. 2H is a partial plan view of a ninth embodiment of a membranelid according to the invention;

[0022]FIG. 3 is a cross-section of a stack of membrane lids wherein eachmembrane lid includes at least one bevel portion to assist in alignment;

[0023]FIG. 4 is an elevational view of an exemplary container accordingto the present invention;

[0024]FIG. 5 is a top plan view of the container of FIG. 4;

[0025]FIG. 5A is a partial sectional view along line 5A-5A of FIG. 5;

[0026]FIG. 5B is a partial sectional view depicting a second embodimentof a lip structure;

[0027]FIG. 5C is a partial sectional view illustrating a thirdembodiment of a lip structure;

[0028]FIG. 6 is an enlarged view of Detail 6 in FIG. 4;

[0029]FIG. 7 is an enlarged view Detail 7 in FIG. 4;

[0030]FIG. 7A is an enlarged view of the second embodiment of the lipstructure;

[0031]FIG. 7B is an enlarged view of the third embodiment of the lipstructure;

[0032]FIG. 8 is a top plan view of an exemplary over-cap for use withcontainers according to the present invention; and

[0033]FIG. 9 is a side elevational view of the over-cap set forth inFIG. 8.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0034] The invention is directed to structures for providing a removableclosure to permit packaging of one or more pieces (i.e., one or morearticles) such as substantially triangular-shaped pieces. In oneapplication, one or more snack pieces may be packaged, and in particularembodiments, one or more substantially triangular-shaped snack piecesmay be packaged to present consumers with an accessible product withminimal breakage. It is contemplated that a wide variety of snack piecesmay be packaged with the structures in accordance with the presentinvention. For example, snack pieces having a substantially triangular,substantially circular, substantially elliptical, substantiallyrectangular, substantially square or other shaped snack pieces such aschips (e.g., tortilla chips, potato chips, vegetable chips, fruit chips,bagel chips), crackers, biscuits, cookies, candy, or the like. Each ofthe above mentioned snack piece shapes could be packaged, for example,with a variety of containers having various alternative shapes such ascontainers having a substantially circular, substantially elliptical,substantially rectangular, substantially square, substantiallytriangular, or other shape. Exemplary containers that can be used withthe inventive concepts of the present invention are disclosed incopending U.S. Provisional Application No. 60/248,340 of Buisson et al.filed Nov. 13, 2000 entitled “An Improved Plastic Package for SnackPieces.” Additional containers and structures relating thereto that mayalso be used with the present invention are disclosed in U.S.Provisional Application No. 60/248,103 of Buisson et al. filed Nov. 13,2000 and U.S. Patent Application No. ______ ______, titled “ContainerBottom and Methods” attorney docket No. 833 1M filed herewith, theentire disclosures of which are incorporated herein by reference. Whileexemplary structures of the present invention are described for use withedible snack pieces, the structures presented herein may be useful tostore, package and/or ship other piece(s), including, but not limitedto, a plurality of frangible or fragile pieces (i.e., a plurality offrangible or fragile articles) in a stacked relationship.

[0035] Structures for providing closure may comprise membrane lids,container lips and/or containers which are particularly suitable forpackaging articles, such as substantially triangular-shaped articles.The membrane lids, container lips and containers according to thepresent invention provide improvements which facilitate packaging,contribute to reduced breakage during packaging, shipping and/orhandling, and/or contribute to maintaining the hermetic seal of thecontainer while presenting a user-friendly membrane lid to a consumerfor removal at will. In particular embodiments of the present invention,exemplary membrane lids, container lips and containers are substantiallytriangular-shaped and may be used, for example, to package substantiallytriangular-shaped articles. Within the context of the present invention,“substantially triangular-shaped” includes a generally three-sidepolygon shape wherein the sides are connected with one another atrespective corner portions and can comprise a sharp angle or a morerounded configuration. In the exemplary membrane lids (e.g., see FIG.1), the rounded corner portions connect straight or substantiallystraight sides. Within the present invention, “straight” may include adistance between the corner portions, rather than requiring any surfaceor cross-sectional configuration of the sides.

[0036] One aspect of the present invention includes membrane lidstructures for providing closure to a container. For example, themembrane lid may have a substantially triangular shape to connect with asubstantially triangular-shaped opening of a container.

[0037] In exemplary embodiments, the substantially triangular-shapedmembrane can have three sides and three corner portions that are eachbisected by an imaginary line. Exemplary membrane lids include one ormore projections that extend outwardly from a substantiallytriangular-shaped perimeter without intersecting the imaginary line ofany adjacent corner portion. Embodiments of membrane lids also includeone or more projections that are non-symmetrically disposed with respectto the imaginary line of any adjacent corner portion or one or moreprojections that extends non-continuously from an adjacent cornerportion and are substantially symmetrically disposed with respect to theimaginary line of the adjacent corner portion. For example, the membranelids can include one or more projections that are interrupted along theimaginary line of an adjacent corner portion. Each of the exemplaryprojections in accordance with the present invention are structured todirect a lifting force to at least one corner portion regardless of thelocation along the perimeter of the membrane.

[0038] Providing one or more projections with one or more of theabove-mentioned structures may reduce or prevent interference of themembrane lid projection(s) with the container lip and/or innerextensions of the over-cap corner portions. After a membrane lid issealed to a container, an over-cap is typically applied over themembrane lid for protecting the membrane lid and/or to permit selectiveclosure of the container once the membrane lid is at least partiallyremoved. Exemplary over-caps that may be used with the inventiveconcepts of the present invention are disclosed in U.S. ProvisionalApplication No. 60/248,089, filed Nov. 13, 2000, and also U.S. patentapplication Ser. No. ______, titled “Substantially Triangular-ShapedOver-Cap” attorney docket No. 8329M filed herewith, the entiredisclosures of which are incorporated herein by reference.

[0039] Any interference between the membrane lid projection and theover-cap tends to reduce the reliability of the connection between theover-cap and the membrane sealed container. For example, interferencebetween the membrane lid projection and over-cap may present asignificant obstacle when applying the over-cap to the container on ahigh-speed assembly line. Moreover, after application of the over-cap,any interference between the projection and over-cap may causeinadvertent disengagement of the over-cap from the container. Forinstance, the above-mentioned interference can present a problem withchanges in atmospheric or external air pressure resulting in changes inthe interior chamber pressure of the container. If the outside airpressure decreases (e.g., that might develop in high altitudelocations), the over-cap may disconnect as the container expands inresponse to increased interior chamber pressure.

[0040] Referring now to the drawing figures in detail, wherein likenumerals indicate the same elements throughout the views, FIG. 1 depictsone exemplary embodiment of a membrane lid 10 comprising a generallyplanar surface 12 having a substantially triangular-shaped perimeter 14.The perimeter of the membrane includes three sides 16 wherein at leastone of the sides (e.g., “16 a”) can be represented by a hidden line. Thehidden lines illustrated throughout the figures demonstrate thesubstantially triangular shape of the perimeter adjacent the one or moreprojections and is not intended to denote perforations or any other typeof alteration to the generally planar surface 12. In one embodiment, themembrane lid 10 has a substantially equilateral triangular-shapedperimeter, wherein the sides 16 of the triangular shape are of equal orsubstantially equal length.

[0041] The membrane lid 10 also includes corner portions 20 a, 20 b, 20c which are shown as rounded but may be more or less angled as desiredand each include an imaginary center line 18 a, 18 b, 18 c that bisectseach corresponding corner portions 20 a, 20 b, 20 c. The membrane lid 10is sized and dimensioned to cover a similarly substantiallytriangular-shaped container, such as a perimeter of a container opening.In one exemplary embodiment, the membrane lid 10 may be used to connectto a container lip 54 located adjacent one end of a container body 52(see FIG. 4 and FIG. 5). The lengths of the sides 16 of the membrane lid10 will be designed to cover the perimeter of the opening and may besealed to the container lip, if provided. In exemplary embodiments, asshown in FIG. 1, the membrane lid has side lengths “L” that can be fromabout 4 cm to about 14 cm, for example from about 6 cm to about 9 cm. Inparticular exemplary embodiments, the side length “L” is from about 7.5cm to about 8.5 cm. The above lengths, however, are for exemplarypurposes only; therefore, the sides may be provided with other lengthsdepending on the particular application.

[0042] As indicated in FIG. 1, the membrane lid 10 can include aprojection 24 extending outwardly from the perimeter 14 of the membranelid 10 without intersecting the imaginary line 18 a, 18 b of anyadjacent corner portion 20 a, 20 b. Although not shown, the membrane lidcould be provided with a plurality of projections, for example,comprising any combination of the exemplary projections describedthroughout this application or their equivalents. When the perimeter ofthe membrane lid is adhered to a surface, each of the membrane lidprojections described herein is dimensioned and located to initiallydirect a lifting force toward at least one of the corner portions.

[0043] As illustrated in FIG. 1, for example, the projection 24 extendsgenerally outwardly from at least one side 16 a of the perimeter 14 suchthat the projection 24 is non-symmetrically disposed with respect to theimaginary lines 18 a, 18 b of adjacent corner portions 20 a, 20 b. Theprojection may also include two tabs 26 a and 26 b that can be arrangedto symmetrically disposed along the perimeter with respect to theimaginary line 18 c of a distal corner portion 20 c. Providing dual tabspermit easy access from a left-handed or right-handed individual and mayassist in removing residual portions of a ripped membrane lid that mightremain after a first attempt to remove the lid. Alternatively or inaddition, the one or more projections described above can include one ormore tabs to extend from two or more sides of the substantiallytriangular-shaped membrane lid, thereby facilitating tab access atdifferent positions of the container relative to the consumer. Moreover,although not shown, the projections described herein may comprise threeor more tabs extending from the perimeter in accordance with the presentinvention. Each tab 26 a, 26 b can be gripped by a consumer at liftingpoint 28 a or 28 b to apply a lifting force to the projection 24 tofacilitate removal of the membrane lid 10 from the container lip orother surface to which the membrane lid is adhered.

[0044] The projections of the present invention are structured todiscourage tearing of the membrane when a consumer applies a liftingforce to at least one tab to remove the membrane lid from the attachedsurface (e.g., a lip of a container). In one embodiment, properdistribution of the lifting force can be accomplished by a projectionwhich substantially covers a lifting area defined by two imaginary linesthat extend from an outer tangential point at each of the two adjacentcorner portions to a lifting point which is used to grip the membranelid for application of the lifting force. The lifting point should beposition a sufficient distance from the perimeter of the membrane lidsuch that a consumer may sufficiently grip the projection to remove themembrane lid from the container. For example, in exemplary embodiments,the lifting point is located at least about 4 mm from the perimeter ofthe membrane lid. In other embodiments, the lifting point is located atleast about 8 mm from the perimeter of the membrane lid. Other liftingpoint distances could also be used in accordance with the presentinvention without departing from the scope of the claims.

[0045] As depicted in FIG. 1, for example, a first lifting area 34 a isat least partially or entirely defined by the perimeter 14 and a firstouter imaginary line 30 a extending from the first lifting point 28 a toan outer tangential point of the first corner portion 20 a and a firstinner imaginary line 32 a extending from the first lifting point 28 a toan outer tangential point of the second corner portion 20 b. A secondlifting area 34 b is at least partially or entirely defined by theperimeter 14 and a second outer imaginary line 30 b extending from thesecond lifting point 28 b to an outer tangential point of the secondcorner portion 20 b and a second inner imaginary line 32 b extendingfrom the second lifting point 28 b to an outer tangential point of thefirst corner portion 20 a. Thus, with reference to FIG. 1, tab 26 a ofthe projection 24 substantially or entirely covers at least the liftingarea 34 a at least partially or entirely defined by the perimeter 14 andlines 30 a and 32 a while tab 26 b of the projection 24 substantially orentirely covers at least a lifting area 34 b at least partially orentirely defined by the perimeter 14 and lines 30 b and 32 b. Theprojection 24 is therefore dimensioned to substantially or entirelycover each of the lifting areas 34 a, 34 b to distribute force over thelifting areas while initially directing the lifting force to at leastone of the adjacent corner portions 20 a, 20 b, thereby reducing theprobability of stress tears by minimizing stress concentrations.

[0046] The projection 24 may also be structured such that the liftingareas 34 a, 34 b define an overlap area 36 to provide additional supportto further discourage tearing of the membrane, for example, when theentire lifting force is applied to a single tab (e.g., either 26 a or 26b). This arrangement removes acute forces in the membrane from a pointclose to the middle of the corresponding side and therefore reduces theprobability of undesired tearing of the membrane.

[0047]FIG. 2A discloses portions of an alternative membrane lid 110 witha surface 112 and a substantially triangular-shaped perimeter 114. Theperimeter 114 includes sides 116 wherein at least one side (e.g., “116a”) can be represented by a hidden line. The membrane lid 110 furtherincludes corner portions 120 a, 120 b, 120 c that are bisected byimaginary lines 118 a, 118 b, 118 c. The exemplary membrane lid 110includes a projection 124 including a single tab 126. The projection 124is non-symmetrically disposed with respect to the imaginary lines 118 a,118 b of adjacent corner portions 120 a, 120 b. As described above,embodiments of the present invention including a single or multiple tabsextending outwardly from a side (e.g., from side “116 a”) may besymmetrically disposed along the perimeter with respect to the imaginaryline 118 c of a distal corner portion 120 c. Optional dual tabs can beprovided to distribute a lifting force and/or to permit easy access froma left-handed or right-handed individual.

[0048] Tabs in accordance with each of the exemplary embodiments of thepresent invention described throughout this application may be locatedcloser to one corner portion or the other such that the tabs are notsymmetrically disposed along the perimeter with respect to any imaginaryline.

[0049] As illustrated in FIG. 2A, the projection 124 includes a singletab 126 which is sized to accommodate gripping by a consumer to apply alifting force to the projection 124 at a lifting point 128 to remove themembrane lid 110 from the container lip or other surface to which it isadhered. The membrane lid 110 is sized and structured to discouragetearing of the membrane when a consumer is lifting the tab 126 to removethe membrane lid 110 from the container or other surface to which themembrane lid 110 is attached. Redirection of the lifting force to reducetearing incidents can be accomplished by structuring the projection 124to substantially or entirely cover a lifting area 134. The lifting area134 is at least partially or entirely defined by the perimeter 114 and afirst imaginary line 130 extending from the lifting point 128 to anouter tangential point of the first corner portion 120 a and a secondimaginary line 132 extending from the lifting point 128 to an outertangential point of the second corner portion 120 b. The projection 124is therefore dimensioned to at least substantially or entirely cover thelifting area 134 to distribute force over the lifting area whileinitially directing the lifting force to at least one of thecorresponding corner portions 120 a, 120 b.

[0050] As further shown in FIG. 2A, the outer perimeter 127 of the tab126 may be curved inwardly such that the tab 126 includes less material.Reducing the amount of material may be desirable to reduce materialcosts while also preventing the tab from obscuring an advertising orother informational display disposed on the exterior surface of thecontainer to which the membrane lid may be attached. However, the outerperimeter 127 should have a sufficient size to permit the tab 126 to atleast substantially or entirely cover the lifting area 134 at leastsubstantially or entirely defined by the perimeter 114 and lines 130,132.

[0051]FIG. 2B includes a membrane lid 210 similar to the membrane lid110 described above. In fact, unless otherwise noted, the membrane lid210 can be identical to the membrane lid 110. However, unlike themembrane lid 110, the membrane lid 210 includes a projection 224 havingan outer perimeter 227 that does not have a reduced portion and does notcurve inwardly. In fact, as shown in FIG. 2B, the outer perimeter 227has straight line portions and, although not shown, may even curveoutwardly. Structuring with outer perimeter such that the projectiondoes not have a reduced portion (e.g., with straight line segments asillustrated) or includes augmented portions (e.g., with outwardly curvedportions) will increase the structural strength of the projections 224,thereby reducing stress concentrations and corresponding tearingincidents.

[0052] FIGS. 2C-2H illustrate alternative embodiments of a projectionthat extends non-continuously from an adjacent corner portion and issubstantially symmetrically disposed with respect to the imaginary linebisecting the adjacent corner portion. A substantially symmetricalprojection will include projections that are symmetrical with respect tothe imaginary line when viewed without the features that provide thenon-continuous extension. Non-continuous extension of the projection canresult from alternate projection material configuration, construction,composition, interruption, or the like when viewing the outer surface ofthe projection and/or through a cross-section of the projection. Forexample, the non-continuous extension can result from a weakened area ofthe projection. The weakened area can include portions of theprojection, or the entire projection, that defines apertures,perforations, slits, scores, crimps, cuts, channels, or otherirregularities. For example, the weakened area could include the entireprojection or a portion less than the entire projection. The weakenedareas in accordance with the present invention are designed to reduce orprevent interference between the inner extension of the over-cap and thecontainer lip and may also reduce or prevent puckering or wrinkling ofthe projection as it is bent down to conform to the outer surface of thecontainer after application of the over-cap.

[0053]FIG. 2C illustrates an exemplary membrane lid 310 wherein theperimeter includes sides 316 wherein at least one of the sides (e.g.,“316 a”) can be represented by a hidden line. At least one cornerportion 320 is bisected by an imaginary line 318 wherein a projection324 extending outwardly from the perimeter 314 adjacent corner portion320 is substantially symmetrically disposed with respect to theimaginary line 318 bisecting an adjacent corner portion 320. Theprojection 324 includes a single tab 326 presenting a lifting point 328for a consumer. The projection 324 extends non-continuously from theadjacent corner portion 320 and includes a weakened area that comprisesportions of the projection that define one or more apertures 338 with aclosed perimeter 340. The aperture 338 may be adapted to preventinterference between the over-cap and portions of the container opening.For example, providing an aperture 338 may facilitate the connectionbetween the inner extensions 78 of the over-cap 70 and the lip 54 of thecontainer 50 by limiting or preventing the projection from interferingwith the connection between the over-cap and the lip. Indeed, theaperture 338 can be located on the projection so that the innerextensions 78 at least partially extends through the aperture 338 toengage the lip 54 when the over-cap 70 is installed on the container 50.

[0054] The symmetrical location of the aperture 338 along the imaginaryline 318 causes the aperture 338 to interrupt the projection 324 alongthe imaginary line 318. In alternative embodiments, the aperture 338 maybe offset from the imaginary line 318 and/or a plurality of aperturesmay be provided such that the projection 324 is not interrupted alongthe imaginary line 318. For example, although not shown, exemplaryembodiments include a plurality of apertures symmetrically offset aboutthe imaginary line 318 without intersecting with the imaginary line 318such that the projection 324 is not interrupted along the imaginary line318.

[0055] As illustrated in FIG. 2C, the aperture 338 can have a half-moonor “D” shape to further prevent interference between the projection 324and the container 50. The projection 324 may need to be reinforced orstructured with increased tearing resistance to prevent failure orripping at the relatively sharp corner portions 342 of the aperture 338.

[0056]FIG. 2D illustrates another embodiment of a membrane lid 410similar to the membrane lid 310 described above and can be identicalunless otherwise noted. For example, the membrane lid 410 also includesa substantially triangular-shaped perimeter 414 with sides 416 whereinat least one of the sides (e.g., “416 a”) can be represented by a hiddenline. At least one corner portion 420 is bisected by an imaginary line418. A projection 424 extends outwardly from the perimeter 414 adjacentcorner portion 420 and is substantially symmetrically disposed withrespect to the imaginary line 418 bisecting the adjacent corner portion420. The projection 424 includes at least one tab 426 and extendsnon-continuously from the adjacent corner portion 420 and includes aweakened area that comprises portions of the projection that define oneor more apertures 438 with a closed perimeter 440. However, unlike themembrane lid 310 illustrated in FIG. 2C, the aperture 438 of themembrane lid 410 includes a perimeter 440 with rounded or smooth cornerportions 442 designed to reduce stress concentrations in the membranewhen applying a lifting force at lifting point 428 to thereby reduce orprevent tearing incidents.

[0057] The aperture 438 in FIG. 2D, as well as apertures in projectionsof any of the embodiments of the present invention, may have asubstantially circular shape. The apertures, if provided in any of theprojections, could also have an oblong shape or other shape to simplifythe manufacturing process and/or enhancing the functional characteristicof the aperture to prevent interference between the over-cap and thecontainer.

[0058] As with the aperture 338, the symmetrical location of theaperture 438 along the imaginary line 418 causes the aperture 438 tointerrupt the projection 424 along the imaginary line 418. Inalternative embodiments, the aperture 438 may be offset from theimaginary line 418 and/or a plurality of apertures may be provided suchthat the projection 424 is not interrupted along the imaginary line 418.For example, although not shown, exemplary embodiments include aplurality of apertures symmetrically offset about the imaginary line 418without intersecting with the imaginary line 418 such that theprojection 424 is not interrupted along the imaginary line 418.

[0059]FIG. 2E illustrates yet another embodiment of a membrane lid 510in accordance with the present invention. The membrane lid 510 can beidentical to the membrane lid described in FIGS. 2C or 2D or otherembodiments described throughout this application including a projectionwith an aperture, unless otherwise noted. For example, the membrane lid510 includes a substantially triangular-shaped perimeter 514 with sides516 wherein at least one of the sides (e.g., “516 a”) can be representedby a hidden line. At least one corner portion 520 is bisected by animaginary line 518. A projection 524 extends outwardly from theperimeter 514 of an adjacent corner portion 520 and is substantiallysymmetrically disposed with respect to the imaginary line 518 bisectingthe adjacent corner portion 520. The projection 524 includes at leastone tab 526 presenting at least one lifting point 528 a, 528 b. Theprojection 524 extends non-continuously from the adjacent corner portion520 and includes a weakened area that comprises portions of theprojection that define one or more apertures 538 to facilitateconnection between the over-cap and the container as described above.

[0060] As with the apertures 338 and 438 described above, thesymmetrical location of the aperture 538 along the imaginary line 518causes the aperture 538 to interrupt the projection 524 along theimaginary line 518. In alternative embodiments, the aperture 538 may beoffset from the imaginary line 518 and/or a plurality of apertures maybe provided such that the projection 524 is not interrupted along theimaginary line 518. For example, although not shown, exemplaryembodiments include a plurality of apertures symmetrically offset aboutthe imaginary line 518 without intersecting with the imaginary line 518such that the projection 524 is not interrupted along the imaginary line518.

[0061] As illustrated in FIG. 2E, the aperture 538, as well as each ofthe apertures described throughout this application, may include anopening 541 providing the aperture 538 with an open perimeter 540. Theopen perimeter allows the membrane lid to be formed with a singleperimeter comprising an outermost perimeter rather than an inneraperture perimeter distinct from an outermost perimeter. Providing asingle outermost perimeter may reduce manufacturing steps and/orotherwise reduce the manufacturing costs for producing the membrane lid.The opening 541 may be a narrow or wide slit or the like. In oneembodiment, the opening 541 extends along the imaginary line 518 thatbisects the corner portion 520 to provide symmetrical division oflifting force when simultaneously lifting the tab at lifting points 528a, 528 b.

[0062]FIG. 2F illustrates another embodiment of a membrane lid 610 inaccordance with the present invention. The membrane lid 610 can beidentical to the membrane lid described in FIGS. 2C-2E or otherembodiments described throughout the present invention unless otherwisenoted. For example, the membrane lid 610 includes a substantiallytriangular-shaped perimeter 614 with sides 616 wherein at least one ofthe sides (e.g., “616 a”) can be represented by a hidden line. At leastone corner portion 620 is bisected by an imaginary line 618. Aprojection 624 extends outwardly from the perimeter 614 of an adjacentcorner portion 620 and is substantially symmetrically disposed withrespect to the imaginary line 618 bisecting the adjacent corner portion620. The projection 624 extends non-continuously from the adjacentcorner portion 620. A weakened area of the projection 624 includes ascored portion wherein the projection includes one or more slits 638.The one or more slits can be formed as cuts that extend entirely throughthe thickness of the projection. In other examples, the slit can beformed as cuts that extend only partially through the thickness of theprojection.

[0063] The symmetrical location of the slit 638 along the imaginary line618 causes the slit 638 to interrupt the projection 624 along theimaginary line 618. In alternative embodiments, the slit 638 may beoffset from the imaginary line 618 and/or a plurality of slits may beprovided such that the projection 624 is not interrupted along theimaginary line 618. For example, although not shown, exemplaryembodiments include a plurality of slits symmetrically offset about theimaginary line 618 without intersecting with the imaginary line 618 suchthat the projection 624 is not interrupted along the imaginary line 618.

[0064] The one or more slits 638 can be shaped in a variety of patterns,such as waved, sinusoidal, arcuate or other shape. Moreover, a pluralityof slits may be provided to further weaken the projection. Asillustrated in FIG. 2F for example, one slit can be intersected with aplurality of cross slits. The arcuate shape of the larger slit isdesigned to substantially match the contact area between the innerextension of the over-cap and the lip to reduce or prevent interferencetherebetween. A single slit, rather than multiple slits, may be providedto weaken the projection to reduce interference without weakening theprojection to the point that it rips or tears when applying a liftingforce to the projection. In alternative embodiments, a plurality ofslits may be provided to further weaken the area to further minimizeinterference. In one example, the slit may be formed as a cross (i.e.,two intersecting slits).

[0065] The slit 638 may be narrow (as illustrated in FIG. 2F) or wide tofacilitate functionality while reducing manufacturing costs. Providing athin cut slit, rather than a wide slit or slot, may be easier tomanufacture and prevent accumulation of scrap material. However, a widerslit or slot may be provided to further reduce interference. A wide slitcan take the form of a channel (i.e., wherein the slit does not extendentirely through the thickness of the membrane lid) or an open slot(i.e., wherein the slit extends entirely through the thickness of themembrane lid).

[0066]FIG. 2G illustrates another embodiment of a membrane lid 710 inaccordance with the present invention. The membrane lid 710 can beidentical to the membrane lid described in FIGS. 2C-2F or otherembodiments described throughout the present invention unless otherwisenoted. For example, the membrane lid 710 includes a substantiallytriangular-shaped perimeter 714 with sides 716 wherein at least one ofthe sides (e.g., “716 a”) can be represented by a hidden line. At leastone corner portion 720 is bisected by an imaginary line 718. Aprojection 724 extends outwardly from the perimeter 714 of an adjacentcorner portion 720 and is substantially symmetrically disposed withrespect to the imaginary line 718 bisecting the adjacent corner portion720. The projection 724 extends non-continuously from the adjacentcorner portion 720. A weakened area of the projection 724 includes ascored portion wherein the projection includes a plurality ofperforations or slits 738. The one or more perforations or slits 738 canbe formed as pinpoint pricks or cuts that extend partially or entirelythrough the thickness of the projection.

[0067] The perforations or slits 738 can by symmetrically ornon-symmetrically disposed about the imaginary line 718. In one example,one or more of the slits intersect the imaginary line to cause aninterruption in the projection 724 along the imaginary line 718. Inalternative embodiments, each of the perforations or cuts 738 may beoffset from the imaginary line 718 such that the projection 724 is notinterrupted along the imaginary line 718. For example, although notshown, exemplary embodiments include a plurality of perforations or cuts738 symmetrically disposed about the imaginary line 718 withoutintersecting with the imaginary line 718 such that the projection 724 isnot interrupted along the imaginary line 718.

[0068] The perforations or cuts 738 may be arranged in a variety ofpatterns along the projection 724. In one embodiment, the perforationsor cuts 738 are arranged in an arcuate pattern to substantially matchthe inner extension 78 from the over-cap 70, thereby minimizinginterference between the over-cap and container lip.

[0069]FIG. 2H illustrates another embodiment of a membrane lid 810 inaccordance with the present invention. The membrane lid 810 can beidentical to the membrane lid described in FIGS. 2C-2G or otherembodiments described throughout the present invention unless otherwisenoted. For example, the membrane lid 810 includes a substantiallytriangular-shaped perimeter 814 with sides 816 wherein at least one ofthe sides (e.g., “816 a”) can be represented by a hidden line. At leastone corner portion 820 is bisected by an imaginary line 818. Aprojection 824 extends outwardly from the perimeter 814 of an adjacentcorner portion 820 and is substantially symmetrically disposed withrespect to the imaginary line 818 bisecting the adjacent corner portion820. The projection 824 extends non-continuously from the adjacentcorner portion 820. A weakened area of the projection 824 includes ascored portion wherein the projection includes one or more crimps 838.

[0070] The crimps 838 can by symmetrically or non-symmetrically disposedabout the imaginary line 818. In one example, one or more of the crimpsintersect the imaginary line 818 to cause an interruption in theprojection 824 along the imaginary line 818. In alternative embodiments,each of the crimps 838 may be offset from the imaginary line 818 suchthat the projection 824 is not interrupted along the imaginary line 818.For example, although not shown, exemplary embodiments include aplurality of crimps 838 offset from the imaginary line 718 withoutintersecting with the imaginary line 818 such that the projection 824 isnot interrupted along the imaginary line 818.

[0071] The crimps 838 may be arranged in a variety of patterns along theprojection 824. In one embodiment, the crimps 838 are arranged in anarcuate pattern to substantially match the inner extension 78 from theover-cap 70, thereby minimizing interference between the over-cap andcontainer lip.

[0072] The above-described embodiments are exemplary in nature and mayinclude other embodiments in accordance with the concepts of the presentinvention. For example, any combination of the above features, or theirequivalents, could be incorporated to provide the non-continuousextension. In addition, while the non-continuous extension of exemplaryembodiments described above have related to projections that aresubstantially symmetrically disposed with respect to the imaginary lineof the adjacent corner portion, the projection can also extendnon-continuously from the perimeter of other embodiments to furtherlimit or prevent portions of the projection from interfering with theconnection between the over-cap and the lip. For example, the projectioncan extend non-continuously from the perimeter while also beingnon-symmetrically disposed with respect to the imaginary line of anyadjacent corner portion. In addition, exemplary membrane lids inaccordance with the present invention can include a plurality ofprojections including one or more of the projections describedthroughout the application or their equivalents (e.g., one or more ofthe projections illustrated in FIGS. 1, 2A-2E, and 3 for example).

[0073] In any of the embodiments described above including a projectionwith a plurality of tabs, the tabs may be joined together with membraneportions having an outer perimeter with a curved perimeter and/or aperimeter without sharp angles that might otherwise provide potentialstress concentration points for membrane tear.

[0074] As described above, providing a projection with a plurality oftabs may assist in left or right handed removal of the membrane lid fromthe container. The additional tabs may also facilitate removal ofresidual membrane lid portions if the membrane lid rips during theprocess of removing the membrane lid from the container. For example, afirst tab might be gripped to remove the lid. After applying a liftingforce, the membrane may inadvertently tear into two portions whereinonly a first portion is removed by the consumer. The second tab couldthen be used to remove the remaining portions of the lid.

[0075] It is also desirable to minimize the amount of material used forthe membrane lids described above to reduce material expenses andminimize the projection hang-over that might otherwise be unsightlyand/or cover portions of the container display surface. The amount ofoverhang or amount of excess membrane material around the remainder ofthe lid which will extend past the point of sealing along a containerlip is typically proportional to the removal functionality of themembrane lid. The amount of overhang can vary from 0 mm, where the sealis at the very edge of the membrane lid, and in other examples canextend to about 3 mm from the seal between the container and themembrane lid. In another example, the overhang of the membrane lid pastthe seal is from about 0 mm to about 1 mm, or in another exemplaryembodiment from 0 mm to about 0.5 mm. In still another embodiment, theoverhang can be wrapped under the lip to which the membrane lid isapplied.

[0076] A variety of materials may be used to fabricate the membrane lid.The membrane lid can be formed of a single piece of monolayer ormultilayer material. Typical multilayer material comprises at least onelayer of an oxygen and moisture barrier material, for example foil, andone layer of sealant, for example a thermoplastic polymer which willseal to a container lip. The layer of sealant can be a coating orcontinuous or non-continuous layer (e.g., coating) to seal with theappropriate surface. For example, the sealant can be applied as anon-continuous layer to the membrane or on the container lip prior tosealing to minimize the amount of sealant, thereby avoiding excess wasteof unused material. In other applications, it can be desired to providethe layer as a continuous layer to one of the remaining layers of themembrane lid in order to simplify formation of the membrane lid from acontinuous sheet of material.

[0077] In one embodiment, the membrane lid is formed of a multilayerlaminate comprising an acrylic primer, a foil layer of about 0.0015 inchthickness, and an ethylene vinyl acetate sealant layer of about 0.00125inch thickness. An adhesive layer may be provided between the foil layerand the ethylene vinyl acetate layer, if desired. The lid membranestructure presented herein can be used with other membrane materialswithout departing from inventive concepts of the present invention.

[0078]FIG. 3 illustrates a stack of membrane lids 1000 where eachmembrane lid 1010 can includes at least one bevel portion 1011 to assistin stacking and aligning a plurality of membrane lids prior to applyingthe membrane lid to the container. In one example, a 6.4 mm horizontaldistance “b₁” could be provided, with an end bevel offset “b₂” of about1.5 mm. Accordingly, each of the embodiments described herein mayinclude a membrane lid with at least one bevel portion to facilitatestacking and aligning of a plurality of membrane lids. Moreover, thebevel portion may be provided on the projection or other areas of themembrane lid and can extend about the entire periphery of the membranelid in additional embodiments.

[0079] The membrane lids in accordance with the present invention may beapplied to the container, adjacent the container opening, with a varietyof attachment techniques. In exemplary embodiments, the membrane lidsare structured to be attached to the container with a heat sealingprocess. In one embodiment, the membrane lid may be applied to acontainer lid by a sealing element at a temperature of greater thanabout 300° F., for example, from about 350° F. to about 450° F. for atime and with a force sufficient to seal the membrane lid to thecontainer lip. In one embodiment, the sealing element applies themembrane lid for about 0.5 seconds to about 1 second and with a pressureof about 80 to about 100 psi. The sealing process and correspondingstructure is designed to provide a hermetically sealed container whileproviding a removable lid having an acceptably low lifting forcerequirement for a consumer to remove the membrane lid from thecontainer.

[0080]FIG. 4 sets forth a container which may be used together with amembrane lid according to the present invention. A suitable container isdisclosed in U.S. Provisional Application No. 60/248,340 filed Nov. 13,2000, to Buisson et al entitled “An Improved Plastic Package for SnackPieces,” Attorney Docket 8332P. The container may optionally include acontainer and/or a container bottom design as disclosed in U.S.Provisional Application No. 60/248,103, filed Nov. 13, 2000, and U.S.application Ser. No. ______ filed on even date to Buisson et al,entitled “Container Bottom And Methods,” Attorney Docket 833 1M.

[0081] As shown in FIGS. 4 and 5, the container 50 comprises asubstantially triangular-shaped container body 52 and an outwardlyextending lip 54 adjacent an upper end of the body 52. FIG. 5 shows atop view of the container 50 which demonstrates that both the lip 54 andthe container body 52 have a substantially triangular-shaped horizontalcross-section.

[0082] It is desirable to structure a container with an opening adaptedto receive a membrane lid, such as one of the membrane lids describedabove, to provide a hermetic seal while also presenting a removableclosure that can easily be removed by a consumer at will. A strongerseal typically requires increased pressure, heat and/or adhesive betweenthe membrane and container opening to provide a seal strength sufficientto provide the desired hermetic condition. However, increasing the sealstrength results in increased effort by the consumer to remove themembrane lid. Moreover, undue seal strength may also result in rippingor tearing of the membrane as the consumer applies the required liftingforce to break the seal and remove the membrane from the container.Therefore, it is desirable to provide a seal sufficient to achieve ahermetic condition while further presenting a user-friendly membrane lidthat may be easily removed when desired.

[0083] As described above, the seal strength is often a function ofpressure, temperature and/or adhesive between the membrane lid and thecontainer during the sealing process. The inherent properties of anon-circular container lip shape may cause uneven vertical rigidity.Uneven rigidity typically causes varying reaction pressures at variouslocations around the lip. To ensure a sufficient hermetic seal at alllocations of the lip, the membrane lid application force must beincreased to provide the minimum required reaction pressure at alllocations around the lip. Accordingly, areas having the lowest rigiditywill have the required minimum reaction pressure necessary to achievethe hermetic seal, however, the points along the lip having a higherreaction pressure will provide an excessive seal strength that may provedifficult for a consumer to overcome.

[0084] To provide a seal that is within the desired strength range, itis beneficial to provide a seal having a substantially constant strengthabout the container opening to thereby avoid sealing areas havingexcessive sealing strength. Accordingly, a substantially uniformreaction pressure may be desired at each point of the seal along the lipwhen pressing the membrane lid against the container during the sealingprocess. Providing a substantially uniform reaction pressure will permitapplication of sealing force sufficient to meet the minimum requirementsof a hermetic seal without having unnecessarily strong sealing areasthat are more difficult to overcome.

[0085] The structure of circular containers having a circular horizontalcross-section generally provide a uniform lip having a uniform reactionpressure when sealing a membrane lid to the container. Accordingly,applying a sealing force to a membrane lid against a conventionalcircular container will typically result in a constant reaction pressureat all contact locations between the container lip and the membrane lid.However, container lips having a substantially triangular-shapedhorizontal cross section may not have an inherently uniform reactionpressure when forcing the membrane lid against the container lip.Rather, attempting to seal a membrane lid to the substantiallytriangular-shaped container lip by applying a sealing force to themembrane lid may result in an uneven reaction pressure at differentpoints of the container lip and therefore varying degrees of sealingstrength between the container lip and the membrane lid. Typically, thelip of a substantially triangular-shaped container inherently has agreater degree of vertical rigidity at the corner portions than at thesides between the corner portions, thereby resulting in a higher degreeof flexing of the sides than the corner portions upon application of asealing force to the membrane lid. Accordingly, by the inherent natureof a substantially triangular-shaped lip, the reaction force andcorresponding reaction pressure will typically be greater at the cornerportions resulting in a higher seal strength at the corner portions thanat the sides between the corner portions. To ensure a sufficienthermetic seal strength at the sides, an increased application force mustbe administered to the membrane lid that will also cause excessivereaction pressure and a correspondingly excessive seal strength at thecorner portions. The increased seal strength at the corner portions maybe difficult to overcome by a consumer attempting to remove the membranelid or may also result in membrane lid tears.

[0086] In accordance with inventive concepts of the present invention,the lip of the substantially triangular-shaped container has sides thatare structured differently than the corner portions to increase therelative rigidity of the sides with respect to the corner portions. Infact, the different structure reduces or substantially preventsdifferences in vertical rigidity between the corner portions and sidesand can result in a substantially constant reaction pressure in responseto a sealing force. Accordingly, with the inventive concepts of thepresent invention, a membrane lid may be sealed to a substantiallytriangular-shaped lip with a substantially constant strength seal aboutthe opening of the container.

[0087] For example, FIGS. 5, 5A, 6 and 7 depict exemplary embodiments ofa container 50 including a lip 54 adjacent an opening of a containerbody 52 wherein the lip 54 has sides 58 structured differently than thecorner portions 56 to increase the relative rigidity of the sides 58with respect to the corner portions 56. Indeed, the different structureof the sides 58 and corner portions 56 provides a lip that exhibits asubstantially uniform reaction pressure when applying a membrane lid tothe lip 54 of the container 50.

[0088]FIG. 6 depicts an enlarged side view of an exemplary cornerportion 56 of the lip 54 from Detail 6 in FIG. 4, while FIG. 7illustrates an enlarged side view of the side 58 of the lip 54 fromDetail 7 in FIG. 4. Moreover, FIG. 5A depicts a cross-sectional view ofthe corner portion 56 and side 58 of the lip 54. The lip 54 has a topsurface 60, an outer wall surface 62, 63 and a bottom surface 64. Inaddition, the outer wall surface 62 of the corner portion 56 has anoutwardly protruding substantially U-shaped configuration with a roundedapex 68. This configuration provides the corner portions 56 withsufficient structural integrity to receive the membrane lid. Incontrast, the sides 58 of the lip 54 are structured differently with asubstantially flat outer wall surface 63 when compared to the U-shape ofthe outer wall surface 62 of the lip corner portions 56. With thisconfiguration, the desired corner portion and side rigidity can beobtained while maintaining a uniform vertical height H₁ from the topsurface 60 to the bottom surface 64 of the lip 54. As illustrated inFIG. 7, while the substantially flat outer wall 63 can have a minordegree of curvature, the outer wall 63 is substantially flat whencompared to the U-shaped profile of the outer wall surface 62 at thecorner portions 56. Modifying the outer wall 63 such that it issubstantially flat, rather than having a U-shaped profile, increases therelative rigidity to the sides 58 with respect to the corner portions56. Accordingly, the combination of the U-shaped outer wall surface 62of the corner portions 56 and the substantially flat outer wall surface63 of the sides 58 provides a substantially triangular-shaped containerlip 54 which exhibits a substantially uniform reaction pressure whenapplying a membrane lid to the lip of the container when compared to thereaction pressure exhibited when applying a membrane lid to asubstantially triangular-shaped container lip with a substantiallyuniform lip structure at the corners and sides.

[0089] While a wide range of protrusion distances may achieve thedesired lip structure, FIG. 6 depicts one embodiment where the distanceL₁ which the lip protrudes beyond the container body, may be from about0.03 to about 0.10 inch. In one particular example, L₁ is about 0.08inch. With reference to FIG. 7, the distance L₂ which the lip protrudesbeyond the container body, may be from about 0.01 to about 0.10 inch. Inone particular example, L₂ is about 0.06 inch.

[0090] The container may be formed with a variety of lip structures toprovide the lip with a substantially uniform reaction pressure whenapplying the membrane lid to the container opening. FIGS. 5B and 7Adepict an alternative embodiment of a container lip 154 in accordancewith additional exemplary embodiments of the present invention. Asillustrated in FIG. 5B, the corner portion 156 is structured similar tothe corner portion 56 of FIGS. 5A and 6 and can be identical. Thecontainer lip 154 includes a top surface 160, a bottom surface 164, andan outer wall surface 162 with an outwardly protruding substantiallyU-shaped configuration with a rounded apex 168. With reference to FIGS.5B and 7A, the container lip 154 further includes sides 158 structureddifferently than the corner portions 156 of the lip 154 to increase therelative rigidity of the sides 158 with respect to the corner portions156. The exemplary sides 158 are structured with an outwardly protrudingsubstantially W-shaped outer wall surface 163 wherein apex areas 167 ofthe W-shaped surface 163 extend outwardly from the container body andare disposed on opposite sides of a recessed central portion 169. TheW-shaped sides 158 have a horizontal thickness T₁ at the apex areas 167and has a greater horizontal thickness than the horizontal thickness T₃of the recessed central portion 169 or the horizontal thickness T₂ ofthe corner portion 156. Such extra horizontal lip thickness at the apexareas 167 may be obtained by creating the W-shaped sides using ablow-molding process. Providing the container lip 154, as illustrated inFIGS. 5B and 7A, with W-shaped sides 158 having increased horizontalthickness T, at the apex areas 167 increases the relative rigidity ofthe sides 158 with respect to the corner portions such that the cornerportions 156 and sides 158 are adapted to exhibit a substantiallyuniform reaction pressure when applying a membrane lid to the lip of thecontainer when compared to the reaction pressure exhibited when applyinga membrane lid to a substantially triangular-shaped container lip with asubstantially uniform lip structure at the corners and sides. Moreover,as with the embodiment of FIG. 7, the structural properties of the lip154 may be achieved with the corner portions and the sides having a wallsurface with the same vertical height between the top surface 160 to thebottom surface 164.

[0091]FIGS. 5C and 7B illustrate additional embodiments of a containerlip 254 includes having corner portions 256 with an outer wall surface262 having a substantially U-shaped configuration with a rounded apex268 and sides 258 with an outer wall surface 263 with rounded apex 267that is similar or identical to the outer wall surface 262. As furtherillustrated in FIG. 5C, the horizontal lip thickness T₁ of the sides 258is larger than the horizontal thickness T₂ of the corner portions 256 toincrease the relative rigidity of the sides 258 with respect to thecorner portions 256 such that the corner portions 256 and sides 258 areadapted to exhibit a substantially uniform reaction pressure whenapplying a membrane lid to the lip of the container when compared to thereaction pressure exhibited when applying a membrane lid to asubstantially triangular-shaped container lip with a substantiallyuniform lip structure at the corners and sides. Moreover, as with theembodiment of FIGS. 7 and 7A, the structural properties of the lip 254may be achieved with the corner portions and the sides having a wallsurface with the same vertical height between the top surface 260 to thebottom surface 264.

[0092] The above embodiments are exemplary in nature. Additionalstructural differences between the sides and corner portions areintended to be encompassed by the present invention as long as the sidesare adapted to exhibit a substantially uniform reaction pressure whenapplying a membrane lid to the lip of the container. Moreover, the term“substantially uniform reaction pressure” is intended to includereaction pressures that are uniform at the corner portions and sides aswell as “substantially uniform” when compared to the differences inreaction pressure between the corner portions and sides when applying amembrane lid to a substantially triangular-shaped container lip with asubstantially uniform lip structure at the corners and sides.Accordingly, a “substantially uniform pressure” may include pressuresthat are different but more uniform than would otherwise be exhibited bycorner portions and sides having substantially the same lip structure.

[0093] In addition, a combination of the embodiments described above canbe applied to arrive at the desired rigidity for the sides and cornerportions. For example, the horizontal thickness of the lip could vary(e.g., as illustrated in FIG. 5C) as well as the profile of the outerwall surface (e.g., as illustrated in FIGS. 5A and 5B).

[0094] In exemplary embodiments of the lip structure, the top surface ofthe lip can extend horizontally from the top of the outer wall surfaceor at an upward angle with respect to the horizontal. Thus, angle “c”(e.g., see FIGS. 6, 7, 7A and 7B) can be from about 0° to about 20°, forexample from about 5° to about 18°, and in one example from about 8° toabout 12°. By arranging the top surface horizontally or at an anglegreater than 0°, the container lip exhibits a spring-like motion when amembrane lid is applied thereto and therefore provides resistance to themembrane sealing force to result in a better membrane lid seal. Theupward angle of the top surface also assists in providing asubstantially uniform reaction pressure along the lip upon applicationof the membrane and alleviates the impact of imperfections in the lipresulting from trimming, mold parting lines and the like. While the topsurface is illustrated as being directed upwardly and inwardly, the topsurface could alternatively be oriented to extend upwardly andoutwardly.

[0095] In one embodiment, a uniformly angled top surface is obtained byusing a mold with a greater top surface angle “c” at the sides than thetop surface angle “c” at the corner portions of the lip. For example, amold may be provided with a top surface corner portion angle “c” ofabout 15° with respect to the horizontal and a top surface side angle“c” of about 20° with respect to the horizontal.

[0096] While the membrane lid and lip structure described above areuseful individually, they may be used in combination. For example, acombination of any of the membrane lids with any of the lip structuresdescribed herein can be used to provide a substantially uniform reactionpressure along the perimeter of the lip upon application of the membranelid to obtain and maintain a hermetic seal while providing a membranelid that can be easily removed by a consumer at will. As described abovethe hermetic seal provided by the membrane lid will create an effectivebarrier against oxygen and moisture

[0097] The containers 50 in accordance with the present invention may beformed by a variety of methods. For example, the container 50 may beformed from a thermoplastic material and can be blow molded, althoughother production methods may be employed. Suitable thermoplasticmaterials include, but are not limited to, polyolefins, such aspolyethylene and polypropylene, vinyl polymers such as ethyl vinylalcohol (EVOH), or the like. These materials may be monolayered and someof the materials may be combined. For example, a multilayer material mayinclude both a polyolefin layer and an EVOH layer. In a specificembodiment, the container 50 is blow molded from a multilayer materialcomprising a layer of EVOH sandwiched between two layers of high densitypolyethylene (HDPE).

[0098] One particular embodiment of the blow-molded, multiple-layerplastic structure of the container is as follows: a virgin polyolefinlayer, a tie layer, a layer of EVOH, another tie layer, and anothervirgin polyolefin layer. Typically, container 50 will also have one ormore layers of regrind material in-between the tie layer and the virginpolyolefin layer. The layer of EVOH might be no less than 0.00005 inchesthick and no thicker than 0.006 inches, for example no less than 0.00005inches and no greater than 0.003 inches and in another example no lessthan 0.0001 inches and no greater than 0.0012 inches.

[0099] An even more particular example of this multilayer plasticstructure comprises a six-layer structure including the following layers(from the outside layer to the inside layer): about 9.31 grams (g) orabout 19.4% by weight of HDPE; about 18.91 g or about 39.4% by weight ofPlant Regrind and HDPE; about 0.62 g or about 1.3% by weight of a tielayer; about 2.02 g or about 4.2% by weight of EVOH; about 0.62 g orabout 1.3% of a tie layer; and about 16.51 g or about 34.4% of PlantRegrind and HDPE.

[0100] Another example of this six-layer structure can comprise (fromoutside layer to inside layer): about 10.7 grams (g) or about 19.4% byweight of HDPE; about 21.66 g or about 39.4% by weight of Plant Regrindand HDPE; about 0.69 g or about 1.3% by weight of a tie layer; about2.33 g or about 4.2% by weight of EVOH; about 0.69 g or about 1.3% of atie layer; and about 18.94 g or about 34.4% of Plant Regrind and HDPE.

[0101] Yet another example of this six-layer structure can comprise(from the outside layer to the inside layer): about 15.0% by weight ofHDPE homopolymer and color; about 63.6% by weight of Plant Regrind (60%by weight) and HDPE homopolymer and color (40% by weight); about 1.4% byweight of a tie layer; about 3.6% by weight of EVOH; about 1.4% of a tielayer; and about 15.0% of Plant Regrind and HDPE homopolymer and color.

[0102] The container will typically have a thickness of from about 0.005to about 0.055 inches, for example from about 0.010 to about 0.045inches. The container body 52 and the lip 54 are integrally formed, forexample, by a blow molding process. Advantageously, the lip structuredescribed herein is self-supportive on the underside of the top surfaceof the lip. Thus, the lip structure may be formed by blow molding whileovercoming the disadvantages of many conventional lip designs whichrequire mechanical support for application of the membrane.

[0103] In another embodiment of the containers according to theinvention, the containers can further include an over-cap 70, an exampleof which is set forth in FIGS. 8 and 9. For example, the over-cap 70could comprise one of the over-caps described in U.S. ProvisionalApplication No. 60/248,089, filed on Nov. 13, 2000, entitled“Substantially Triangular-Shaped Over-Cap,” and U.S. application Ser.No. ______ filed on even date, entitled “Substantially Triangular-ShapedOver-Cap,” to Buisson et al., Attorney Docket 8329M, which areincorporated herein by reference.

[0104] The exemplary over-cap 70 of FIGS. 8 and 9 comprises asubstantially triangular-shaped top surface 72 and a skirt 74 extendingsubstantially downwardly from the perimeter 76 of the top surface 72. Asis further shown in FIGS. 8 and 9, the skirt 74 includes substantiallyrounded corner portions and substantially straight sides extendingaround the perimeter 76 of the top surface 72. The skirt corner portionsinclude inner extensions 78 while the skirt sides are substantially freeof inner extensions. As used herein, “substantially free of innerextensions” includes instances wherein the skirt sides have asufficiently small percentage of such inner extensions such that thecorner portion inner extensions are not prevented from moving inwardwhen an outward pressure is exerted on the underside of the over-cap. Inone embodiment, the skirt sides are free of inner extensions. The skirtincluding corner portions having inner extensions and skirt sidessubstantially free of inner extensions provides the over-cap with theability to securely attach to the lip 54 of the container 50 describedherein and resist pressure differentials between inner and outer sidesof such a container. Advantageously, this structure also allows easyremoval of the over-cap from such a container when desired by aconsumer.

[0105] The specific embodiments and examples set forth above areprovided for illustrative purposes only and are not intended to limitthe scope of the following claims. Additional embodiments of theinvention and advantages provided thereby will be apparent to one ofordinary skill in the art and are within the scope of the claims.

What is claimed is:
 1. A membrane lid comprising: a) a surface includinga substantially triangular-shaped perimeter with first, second and thirdcorner portions, wherein each corner portion is bisected by an imaginaryline; and b) a projection including a tab and adapted to initiallydirect a lifting force to at least one of the corner portions, whereinthe projection either extends outwardly from the perimeter such that theprojection is non-symmetrically disposed with respect to the imaginaryline of any adjacent corner portion, or the projection extendsnon-continuously from an adjacent corner portion and is substantiallysymmetrically disposed with respect to the imaginary line of theadjacent corner portion.
 2. The membrane lid of claim 1, wherein theprojection extends outwardly from the perimeter such that the projectionis non-symmetrically disposed with respect to the imaginary line of anyadjacent corner portion.
 3. The membrane lid of claim 2, wherein theprojection includes a lifting point and a lifting area, the lifting areabeing defined by a first imaginary line extending from the lifting pointto an outer tangential point of the first corner portion and a secondimaginary line extending from the lifting point to an outer tangentialpoint of the second corner portion, and wherein the projectionsubstantially covers the lifting area.
 4. The membrane lid of claim 2,wherein the projection includes first and second lifting points andfirst and second lifting areas, the first lifting area being defined bya first outer imaginary line extending from the first lifting point toan outer tangential point of the first corner portion and a first innerimaginary line extending from the first lifting point to an outertangential point of the second corner portion, and the second liftingarea being defined by a second outer imaginary line extending from thesecond lifting point to an outer tangential point of the second cornerportion and a second inner imaginary line extending from the secondlifting point to an outer tangential point of the first corner portion,and wherein the projection substantially covers the first and secondlifting areas.
 5. The membrane lid of claim 2, wherein the projectionextends non-continuously from the perimeter.
 6. The membrane lid ofclaim 1, wherein the projection extends non-continuously from anadjacent corner portion and is substantially symmetrically disposed withrespect to the imaginary line of the adjacent corner portion.
 7. Themembrane lid of claim 6, wherein the projection comprises a weakenedarea.
 8. The membrane lid of claim 7, wherein the weakened area includesportions of the projection that define an aperture.
 9. The membrane lidof claim 8, wherein the aperture has an open perimeter.
 10. The membranelid of claim 9, wherein the projection defines a slit in communicationwith the aperture to provide the open perimeter.
 11. The membrane lid ofclaim 8, wherein the aperture has a closed perimeter.
 12. The membranelid of claim 8, wherein the aperture is bisected by one of the imaginarylines.
 13. The membrane lid of claim 7, wherein the weakened areaincludes a scored portion of the projection.
 14. The membrane lid ofclaim 13, wherein the projection is scored by perforating theprojection.
 15. The membrane lid of claim 13, wherein the projection isscored by cutting the projection.
 16. The membrane lid of claim 15,wherein the cut extends only partially through the thickness of theprojection.
 17. The membrane lid of claim 15, wherein the cut extendsentirely through the thickness of the projection.
 18. The membrane lidof claim 13, wherein the projection is scored by crimping theprojection.
 19. The membrane lid of claim 1, wherein the perimeter has asubstantially equilateral triangular shape.
 20. The membrane lid ofclaim 1, formed of at least one layer of foil and at least one polymerlayer.
 21. The membrane lid of claim 1, formed from a multi-layerlaminate comprising an acrylic primer, a foil layer, and an ethyl vinylacetate sealant layer.
 22. The membrane lid of claim 1, furthercomprising a bevel portion.
 23. The membrane lid of claim 1, wherein theprojection is interrupted along the imaginary line of an adjacent cornerportion.
 24. The membrane lid of claim 1, wherein the projection extendsoutwardly from the perimeter without intersecting the imaginary line ofany adjacent corner portion.
 25. The membrane lid of claim 1, whereinthe tab comprises a plurality of tabs.
 26. The membrane lid of claim 1,wherein the projection comprises a plurality of projections.
 27. Acontainer comprising a lip having a substantially triangular-shapedhorizontal cross-section, the lip including three corner portions andthree sides, wherein the sides of the lip are structured differentlythan the corner portions of the lip to increase the relative rigidity ofthe sides with respect to the corner portions such that the cornerportions and the sides are adapted to exhibit a substantially uniformreaction pressure when applying a membrane lid to the lip of thecontainer.
 28. The container of claim 27, wherein the lip comprises atop surface, an outer wall surface and a bottom surface, and the cornerportions of the lip having an outwardly protruding substantiallyU-shaped outer wall surface.
 29. The container of claim 27, wherein thesides of the lip have an outwardly protruding substantially U-shapedouter wall surface.
 30. The container of claim 27, wherein the sides ofthe lip have an outwardly protruding substantially W-shaped outer wallsurface.
 31. The container of claim 27, wherein the sides of the liphave a substantially flat outer wall surface.
 32. The container of claim27, wherein a horizontal thickness of the lip is substantially the sameat the corner portions and at the sides.
 33. The container of claim 27,wherein a horizontal thickness of the lip is substantially greater atthe sides than at the corner portions.
 34. The container of claim 27,wherein the lip comprises a top surface and an outer wall surface,wherein the top surface extends from the top of the outer wall surfaceat an upward angle with respect to the horizontal.
 35. The container ofclaim 27, further comprising a membrane lid comprising: a) a surfaceincluding a substantially triangular-shaped perimeter with first, secondand third corner portions, wherein each corner portion is bisected by animaginary line; and b) a projection including a tab and adapted toinitially direct a lifting force to at least one of the corner portions,wherein the projection either extends outwardly from the perimeter suchthat the projection is non-symmetrically disposed with respect to theimaginary line of any adjacent corner portion, or the projection extendsnon-continuously from an adjacent corner portion and is substantiallysymmetrically disposed with respect to the imaginary line of theadjacent corner portion.